I have read on the official iRex forum:
"Which Languages does the iLiad support?
Currently the iLiad supports: English, Dutch and Simplified Chinese.
German, Korean, French and Spanish will be available shortly.
Additional language support is planned in the future".http://forum.irexnet.com/viewtopic.php?t=4

But if I need Cyrillic language support, can I use iLiad right now? I know that interface will be on English, but I just need correct displaying of Cyrillic (Russian) text.

As I understand rightly, it's enough to prepare PDF with embedded Cyrillic font. And iLiad will use this embedded font. Will it work?